Think Biomass, Not Natural Gas

The framework of energy supply and use by any country is confoundingly complex. Now try to speculate what it might be 40 years from now, assuming a drastic reduction in carbon dioxide emissions. Not so easy, eh?

But there are people doing it: going to work each day, considering myriad energy sources, conjuring up possible configurations for the future. It’s an undertaking many might find intriguing, but … understanding all the technologies, constantly crunching the numbers, seeing a big picture that is as complex and immutable as a monotone jigsaw puzzle, butting up against obstacles and being ready to accept new information that may topple the apple cart — that’s another thing.

Jeffrey Greenblatt, project scientist at the Lawrence Berkeley National Laboratory, is one of the people in these trenches. He’d like to “electrify the economy” to limit atmospheric carbon dioxide.

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He and colleagues, a team of 50 scientists, engineering and utility professionals led by Jane Long of Lawrence Livermore National Laboratory, are nearing the end of a study titled California’s Energy Future. Their task: determine if and how California could reduce its carbon emissions 80 percent below 1990 levels by 2050, in line with an executive order issued by then-Gov. Arnold Schwarzenegger. It’s a goal so ambitious as to elicit “ah, sure” groans, but reductions at this level will likely be required to keep atmospheric CO2 in the 350 to 450 parts per million range in 2050, what most climate scientists say is needed to prevent runaway global warming. The latest measure of CO2 in the atmosphere recorded at the Mauna Loa Observatory was about 391 ppm, taken at the end of January.

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They are imagining what is possible and yet what may well be an impossibility, given a variety of limitations — political will, cost, the messiness of a free society. They do not expect their findings to be implemented quickly or in toto, and they’re not recommending a course of action. What they are doing is providing scenarios that could reach the 80 percent reduction.

“Our conclusion is certainly not that all we have to do is push renewables, push efficiency or push nuclear,” Greenblatt said. “You’ve got to push them all.”

The team placed a cap of carbon emissions at 80 million metric tons of carbon dioxide per year by 2050 — in 2008, the state currently belched forth 474 million metric tons — and developed several scenarios for various energy sources. They assumed a 2.75 percent rate of growth, consistent with long-term historical growth in the state. Although the study addresses California and its economy, Greenblatt said findings will be apropos to “any developed nation.”

Others have addressed the issue on a global level. The World Wildlife Fund and Ecofys (a Netherlands-based think tank focused on sustainable energy solutions) recently released an international study titled The Energy Report: 100% Renewable Energy by 2050. The authors believe the world could run almost entirely on renewable energy by that year, after paring down energy demand through intense energy efficiency measures and lifestyle changes (among them less air travel and a halving of meat consumption in developed countries).

At last year’s Society of Environmental Journalists’ annual conference, Greenblatt talked of electrifying the energy sector by relying heavily on renewable energy, of including nuclear and carbon sequestration with coal generation and of limiting other fossil fuel use to areas where only those fuels could do the task or were needed to supplement the supply of biofuels. He talked of heating buildings with electricity with the aid of heat pumps and using natural gas “like an expensive perfume.”

That’s when the ears of so-many journalists perked up. Few had heard or considered the idea that electricity could better heat homes than natural gas — labeled a “clean” fossil fuel and used widely to heat homes and offices because of its efficiency.

In a later interview, Greenblatt took on the skeptics.

“You have to think beyond the current paradigm,” he said. “ [In the future] we’re not burning fossil fuels to make our electricity anymore. That energy is coming from the sun, wind, waves, biomass and geothermal. You’re getting all this energy that is very low carbon and then you’re using electricity to move heat into homes at something like the efficiency of two and a half to three times the efficiency of a furnace. In other words, for every unit of energy consumed by the heat pump, you can get two to three units of heat actually in your house.”

Interviewing Greenblatt and Max Wei, a senior research associate and part of the team, is an eye-opening experience. One learns that certain industrial processes — making glass and cement, for example — are likely never going to be feasible with heat pumps and electricity because to date only fossil fuels can attain the required temperatures. One also learns that trains and buses can be fairly easily electrified and that we may be able to convert biomass starter materials directly to fuels using engineered microbes.

The paper is being organized around four scenarios: options that are heavy renewable, nuclear, biomass and fossil fuels (coal and natural gas are used for generation with carbon sequestration).

We can get this much wind, but can we get the transmission for it and at what cost? Nuclear is a dependable base-load electrical provider, but will there be a way to solve the waste disposal problem? Will there be a breakthrough that makes hydrogen fuel cells more cost effective for use in vehicles? We could grow biomass for fuel, but we need fossil fuels to do it. Would it be better to burn the biomass for electricity if we could sequester the carbon?

“Basically, we have four possible pathways that are low-enough carbon they’re worth considering,” he said. “One, which is not worth considering, is burning more natural gas. It’s not going to save enough carbon. It doesn’t get us far enough.”

But there are problems with all the scenarios. “Technically you could build a lot of your power with nuclear,” he said. “But with nuclear there’s a fuel-waste disposal issue and a public acceptance issue that’s huge.

“There is enough renewable energy (mainly solar, wind and geothermal) to run most of our energy system. The challenge there is transmission, land-use impacts and the 800-pound gorilla — load balancing — the fact that these are mostly intermittent, and you’re going to have unpredictability in your energy grid,” he said.

Originally, biomass had been relegated to a smaller role, but several colleagues at the laboratory called for considering such a scenario even though providing massive amounts of electricity from biomass would seem, at this point, to be something more easily done on paper than in a real economy.

The biomass option relies on California securing about 15 percent of available biomass in the country (which is also the percentage of U.S. population California will likely have in 2050). It could include agricultural waste, forest residue, municipal wastes, construction debris, organic effluent from sewage, organic compostable material now going to landfills, second-generation biofuels and some energy crops such as corn and perennial grasses grown on marginal lands. Some biomass might be imported internationally.

The biomass would be transported and burned in integrated gasification-combined cycle generators (possibly modified coal plants), built or retrofitted to release a relatively clean stream of CO2. That carbon dioxide could be sequestered, resulting in a net decrease in CO2 in the atmosphere. (Unlike coal or natural gas, new biomass grows, sequestering carbon.)

Asked if there were other environmental concerns from burning biomass, Greenblatt said it will produce “tars and other gunky stuff you have to deal with” but added those problems fall outside the purview of this study.

The net decrease in carbon emissions realized with biomass/sequestration gives the transportation scenario some breathing room, he said. It adds another option to the puzzle. The study considers a future where much of the small-vehicle fleet is electrified, but aviation and long-haul trucking still require liquid fuels, a good part of which will be fossil fuels.

“Getting enough biomass to run the energy system is a challenge,” Greenblatt said. “It comes with an assumption that we’re pushing aggressively on both efficiency and electrification — keeping the demand for transportation fuels way down compared to what it would have been if we continued business as usual.”

Even with increased efficiency and electric plug-ins, the transportation sector, which now consumes more than a third of the nation’s fossil fuels, remains a difficult nut to crack. “We try to squeeze as much liquid fuel demand out of the transportation sector as possible to start with,” he said.

Plug-in electrics have a limited range and battery technology, at least to date, which precludes long-range travel, or, as Greenblatt phrased it, cars are “mobile power plants” that have “an energy density constraint.” The team is looking at hydrogen-powered cars as a way of providing long-range transportation options.

Carbon sequestration is often linked with coal power and is not considered a proven technology, but that hasn’t deterred Greenblatt. “If we only looked at the technologies you can go out and buy today we wouldn’t get very far. The caveat here is we have to make sure it works at large scale. If it does, then these options become available to us.”

The study team has looked at sequestration for a broad range of fuels. “Sequestration is a technology that is in demonstration in multiple locations around the world,” Greenblatt said. “Many pieces of the technology are well understood. There’s still a lot of work to be done before it becomes a viable large-scale technology. But we felt the promise of it was so great it was worth considering as a possibility.”

Questions that emerge from this discussion often relate to numbers, but the authors aren’t releasing their data prior to release of the study on Friday.

Greenblatt was the author of the study Clean Energy 2030 prepared for Google, Inc. in 2008. It looked at ending use of coal and oil for electricity generation and cutting petroleum use in cars by 44 percent by 2030 nationwide.

That study, which calls for reducing energy demand by 33 percent through aggressive efficiency measures, adding 710 gigawatts of power from renewables, and transferring 41 percent of the nation’s vehicle fleet to plug-ins, estimated the cost of the suggested course of action at $3.86 trillion in 2008 dollars and a savings of $4.68 trillion for a net savings of more than $820 billion over the plans’ 22 years.

When asked about costs for the California study, Greenblatt said they have cost estimates, but extrapolating to 2050 won’t be a part of the study, other than projected estimates of increases and decreases in costs of various technologies. He said authors will discuss cost as one of many issues, including policy, resource and infrastructure constraints.

“What we wind up showing the reader is that there are a number of choices that could approximately meet our goal,” Greenblatt said. “They all have challenges; the challenges differ. They’re all difficult, but it’s hard to say ahead of time which one will be a show-stopper and which one won’t, so we wind up presenting a portfolio of which you can choose one or some sort of hybrid of them.”

The study will present the scenarios and various options, creating what could be an intriguing tool for contemplating our energy future. If only making energy choices and implementing change were as easy as putting a puzzle together.

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